This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. A region of the STAU protein has been crystallized and I have obtained native diffraction up to 1.5 angstroms. I am now trying to obtain phase information using the anomolous signal of either I3C (5-amino-2,4,6-triiodoisophthalic acid), or Hg (ethyl mercuric phosphate), which have been soaked into the crystals. Obtaining the previously unkown structure of this protein is very important to understanding the mechanism of Stau mediated decay, which is a mechanim studied in Lynne Maquat`s lab where I am a postdoc. This mechanism conditionally degrades mRNA in a translationally dependent manner when STAU is bound to its cognate RNA target, thus controlling that particular protein`s abundance in the cell.